Mercury switch



March 28, 1939. C H LARSON 2,151,923

MERCURY SWITCH Filed Dec. 24, 1934 2 Sheets-Sheet 1 F 2 Z? A9 1.9

r; zle g ar arson March 28, 1939. I QHLARSON I 2,151,923

MERCURY SWITCH Filed Dec. 24, 1934 2 Sheets-Sheet 2 17102271257" 'arl flcfarson Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE MERCURY SWITCH Carl H. Larson, Elkhart, Ind., assignor to The Adlake Compa y, a. corporation of Illinois Application December 24, 1934, Serial No. 758,879

17 Claims. (Cl. 20097) electrode 22 is determined by the position within the envelope of a displacer or plunger 26.

As common with switches of this general character, the envelope is evacuated and filled with an inert gas (such as helium hydride, helium, hydrogen, or the like) before being sealed oil at 2i. i

The displacer 26 comprises an iron sleeve 28, interiorly fitted with an elongated glass thimble the description is read in conjunction with the 29, both ends of which project beyond the iron accompanying drawings, in which sleeve it. Guide washers 3!] provided at inter- Figs. 1-4. inclusive show various positions of a vals along their peripheries with lugs engaging hack contact switch made in accordance with this the walls of the envelope fit over the projecting invention; ends of the glass thimble 29 and guide the dis- Figs. 5-7 inclusive show various positions of a placer in its vertical movement within the enfront contact switch made in accordance with velope. The washers are held in place by springs this invention. 311 which also serve to protect the switch during But this specific illustration and the correshipping. spending specific description are for the purpose The top of the displacer is equipped with aof disclosure only and arenot to be construed as time delay ele generally designated imposing limitations on the claims except as rewhich permits gas to pass slowly to and from the quired by the prior art. interior of the displacer whenever there is a gas The switches of this invention are of the type pressure differential which tends to move the gas. in which a magnetically controlled plunger or The time delay element in the present embodidisplacer determines by its position within the ment of the invention consists of a small openi g switch the height of a mercury column and hence 33 in the top wall of the glass thimble, 29, and the condition of the electrical circuit through the plugs 3 3 and 35 of cotton separated by a layer switch. A coil ill is associated with each switch of ceramic powder 36. The resistance which the and is intermittently energized, as for example cotton plugs and ceramic powder offer to the so by a synchronous motor ll driving a cam [12 pas age of ga m y b j d by the tightness which operates a circuit breaker i3 in a circuit with which the wads are packed n the th mbl which includes a coil it and an electromotive and the amount of powder that-is used. iorce i l. Other means for intermittently ener- The d spl e! has an Opening 37! through its gizing the coil ill may, of course, be used. side wall at a point just above the level of the 35 The switches are mounted within the coil it} mercury when the switch is in de-energized posiand the air gap for operating the switches is fixed ticn (See Fig- 1)- n s D O the mercury "by providing pole sleeves i5 and it of magnetic level is such that the electrodes 2i and 22 are material connected exteriorly by an iron yoke ill. b dge by the mercury- The switches are held in place by sleeves iii of As soon as the enlarged portion of the cam 40 non-magnetic material which yieldingly grip the Which is minted in the direction f the a w switch envelopes in the region of th air gap strikes the circuit breaker it, the coil ill becomes energized and the magnetic flux between the Back contact switch (Fzgspoles it and it draws the plunger 26 down to the The baclr contact switch, generally designated pgsltton Shown-m l 9, shown in Figs. l-i comprisesaswitch envelope This Plownwam movement 9 plunger 2@, preferably of glass, through the bottom oi causes i mgrcurylevel on the Outslde h which electrodes 21] and 22 are sealed. The cendlsplacel but the gas entrapped l tral electrode 2i is surrounded by a glass sleeve the space 38 forces the mercury Withm the d15- lacer away from. the bared end of the electrode for the manor portion oi its length and the p i b d d f th 1 t d b t 26, thus opening the circuit. The difference in are en 0 e 8 ec e 15 en wlthflts the outside'and inside mercurylevels creates a end m extendmg below the top of the msulatmg gas pressure differential which tends to become Sleeve equalized as the gas within the space 38 slowly The envelflpe contain-S q y of mercury passes through the timedelay element 32, and as 25, the level of which with respect to the central this equalization process takes place, the mercury level on the outside of the displacer gradually falls and that on the inside gradually rises. However, before the mercury on the inside of the displacer has time to make contact with the end 24 of the electrode 2|, the cam 12 has rotated a sufilcient amount to bring the circuit breaker 18 to the rearward edge of the enlarged portion of the cam (see Fig. 3) and as soon as the circuit through the coil I8 is opened, the displacer 26 rises by its buoyancy to the position shown in Fig. 1 momentarily carrying with it a quantity of mercury within the displacer. At the instant, however. when the opening 31 rises above the outside mercury level (which of course falls rapidly as the displacer rises), the mercury column within the displacer is undermined and the switch parts almost instantaneously take the position shown in Fig. 1 with the mercury level the same on the inside and outside of the displacer.

Inasmuch as the circuit through the electrodes II and 22 is closed when the coil is de-energized, it naturally follows that any lower position of the displacer will effect the closing of the circuit if the time delay element 32 is given an opportunity to equalize the gas pressures on the inside and outside of the displacer. For example, should the coil 18 become permanently energized as distinguished from intermittently energized by reason of an open circuit through the motor H, the mercury in the switch would finally level 011' as shown in Fig. 4, leaving the circuit through the switch closed.

This feature is very important in many circuits where it is desirable to have the circuit through the switch closed in case the intermittent energization of the switch ceases.

Front contact relay (Figs. 5-7) The front contact switch, generally designated 45, shown in Figs. 5-7 inclusive, performs the same function as the switch shown in Figs. 1-4 with respect to closing the circuit through the switch whenever the intermittent energization of the coil ceases.

The switch comprises an envelope 46, electrodes 41 and 48, a mercury fil1 48, an insulating sleeve 58 around the central electrode 41, and a displacer generally designated 5|. In so far as these parts resemble the back contact switch shown in Figs. 1-4 inclusive, they will not be described in detail here, and corresponding reference characters will be used.

When the coil I0 is energized, the displacer is lifted completely out of the mercury, and the mercury level within the switch envelope is such that it contacts with the bared end of the electrode 41 thus closing the circuit between the electrodes 41 and 48. When the cam 12 rotating in the direction of the arrow opens the circuit through the coil Hi, the displacer 5| falls by gravity to the position shown in Fig. 6 forcing mercury away from the central electrode 41 due to the gas pressure differential between the inside and outside of the displacer.

In normal operation, the coil I0 is again energized before the mercury column within the displacer has a chance to make contact with the bared end of the central electrode 41 by the escapement of gas through the time delay element 32, thus lifting the displacer to the position shown in Fig. 5. As the plunger moves upwardly due to energization of the coil, a column, of mercury is carried up within the displacer, but as soon as the outside mercury level falls below the bottom of the glass thimble 28, the mercury falls away from the displacer so that the switch parts take the position shown in Fig. 5 almost instantly upon energization of the coil l0.

Should, for any reason, the intermittent energization of the coil H1 cease, as for example by an open circuit through the motor II, the mercury column within the displacer will have sufilcient time to rise and close the circuit through the electrodes 41 and 48 (see Fig. 7).

As in the back contact switch, any position of the displacer effects the closing of. the circuit between the electrodes 41 and 48 if the time delay 32 is given a sufficient time to operate. If not, the switch operates as a. front contact switch.

When the principles underlying the invention are fully understood, many modifications will suggest themselves to those skilled in the art. For example, tilting type mercury switches may be equipped with time delay elements to accomplish the desired functions.

The circuit breakers disclosed herein are not limited in their use to an intermittently operated control circuit. There may be situations in which it is desirable to open a circuit for a given period of time and then close it again, this entire function to take place upon the happening of some event, as for example, the energization or deenergization of a relay coil. The switches of this invention are admirably suited to this purpose.

I claim:

1. In a circuit breaker of the class described, comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, means for shifting the mercury to change the condition of the circuit through the electrodes, a time delay element adapted to restrain the movement of mercury toward but not away from one of said electrodes, the quantity of mercury in the envelope and the elevation of the electrodes being such that the electrodes are bridged by mercury except when the time delay element is temporarily withholding the mercury from said one electrode.

2. In a circuit breaker of the class described comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, 9. displacer for shifting the mercury level to change the condition of the circuit through the electrodes, a time delay element adapted to restrain the movement of mercury toward one of said electrodes, the quantity of mercury in the envelope and the elevation of the electrodes being such that the electrodes are bridged by mercury at all positions of the displacer with the exception of the period during which the time delay element is functioning to restrain the movement of mercury toward said one electrode.

3. A circuit breaker of the class described comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, a displacer telescoped over one of the electrodes for shifting the mercury to change the condition of the circuit through the electrodes, a time delay element carried by the displacer and comprising a restricted gas passage for restraining the movement of mercury toward, but not away from, said electrode, the quantity of mercury in the envelope and the elevation of the electrodes being such that the electrodes are bridged by mercury except when the time delay element is temporarily withholding the mercury from said one electrode.

4. A circuit breaker of the class described comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, means including a plunger for shifting the mercury to change the condition of the circuit throughthe electrodes, a time delay element telescoped over one of said electrodes and comprising a. restricted gas passage for restraining the'movement of mercury toward said electrode, the quantity of mercury in the envelope and the elevation of the electrodes being such that the electrodes are bridged by mercury not only when the plunger is in its raised position, but also when in lowered position, except for the period during which the time delay element is functioning to restrain the movement of mercury toward said one electrode.

5. In a circuit breaker of the class described, a switch envelope, spaced electrodes sealed through the envelope, a mercury fill, means to shift the mercury to change the condition of the circuit through the electrodes, and a time delay element associated with one of the electrodes adapted to delay the movement of mercury toward, but not away from, circuit closing position, the quantity of mercury and the elevation of the electrodes being such that the electrodes are bridged by mercury except when the time delay element is by its action restraining the movement of mercury toward one said electrode.

6. In a mercury switch, a switch envelope, spaced electrodes in the envelope, a mercury fill adapted to be manipulated to make or break an electrical circuit through the electrodes, a time delay element for restraining the movement of mercury toward circuit closing position, the quantity of mercury and the elevation of the electrodes being such that the mercury bridges the electrodes whenever the mercury within the envelope is at rest.

7. In a circuit breaker adapted to open and close an electrical circuit. whenever the circuit breaker is intermittently operated at or above a predetermined frequency, the combination of a container, a pair of electrodes in the container, a quantity of mercury in the container adapted to be moved with relation to the electrodes to open or close the electrical circuit through the electrodes, and means within the container for limiting the time during which the circuit through the electrodes may under any circumstances continuously remain open, said means including a time delay element associated with one of the electrodes.

8. In a circuit breaker close an electrical circuit whenever the circuit breaker is intermittently operated at or above a predetermined frequency, the combination or a container, a palr of electrodes in the container, a quantity of mercury in the container, and movable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through theelectrodes, said means, mercury and electrodes being so proportioned as to cooperate to close the circuit through the electrodes after said means remains at rest for a predetermined period of time at any point in its movement.

9. A mercury switch comprising a switch envelope, spaced electrodes having bared portions therein, a mercury fill normally bridging the electrodes, a hollow plunger. telescoped over one of the electrodes and movable between an upper position and a lower position for temporarily opening the circuit through the electrodes when the plunger is intermittently operated at or above a prede; termined frequency, the parts being proportioned so as to cause the mercury to bridge the electrodes when the plunger is in its upper position and to be displaced from one of the electrodes when the adapted to open and plunger is in its lower position, and means associated with the plunger, including a time delay device, for restoring the displaced mercury to bridging relation with the electrodes after the plunger remains in its lower position for a predetermined period of time.

10. In a relay, a coil, a mercury switch associated with the coil and comprising a switch enswitch envelope, spaced electrodes having bared portions therein, a mercury fill normally bridging the electrodes, a hollow plunger telescoped over one of the electrodes and movable downwardly to displace the fill from said electrode and open the circuit, said plunger having an opening in its side wall for admitting gas to the plunger when the level of mercury outside the plunger is at or below the opening and having a time delay means operable on the gas in the plunger above said opening, said means comprising a restricted gas passage for relieving pressure in the plunger and permitting the mercury therein to rise to bridge the electrodes.

12. A back contact relay adapted to open and close an electrical circuit whenever the relay is intermittently operated at or above a predetermined frequency, said relay comprising the combination of a container, a pair of electrodes in the container, a quantity of mercury in the container, movable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through the electrodes, and a coil for operating said movable means to shift the mercury to open the circuit through the electrodes when the coil is energized and close the circuit when the coil is deenergized, said means, quantity of mercury and electrodes being so proportioned as to cooperate to close the circuit through the electrodes after said means remains at rest for a predetermined period of time at any point in its movement.

13. A back contact relay adapted to open and close an electrical circuit whenever the relay is intermittently operated at or above a predetermined frequency, said relay comprising the combination of a container, a pair of electrodes in the container, a quantity of mercury in the container, movable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through the electrodes, and a coil for operating said movable means to shift the mercury to open the circuit through the electrodes when the coil is energized and close the circuit when the coil is deenergized, said means, quantity of mercury and electrodes being so proportioned as to cooperate to close the circuit through the electrodes after said coil remains energized for a predetermined period of time.

14. A back contact relay adapted to open and close an electrical circuit whenever the relay is intermittently operated at or above a predetermined frequency, said relay comprising the combination of a. container, a pair of electrodes in the container, a quantity of mercury in the container, movable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through the electrodes, a time delay device associated with the container, anda coil for operating said movable means to shif trodes when the coil is energized and close the circuit when the coil is deenergized, said means, quantity of mercury and electrodes being so proportioned as to cooperate with the time delay device to close the circuit through the electrodes after said coil remains energized for a predetermined period of time.

lation to the electrodes to close or open the electrical circuit through the electrodes, and a coil for operating said movable means to shift the mercury to close the circuit through the electrodes when the coil is energized and open the circuit when the coil is deenergized, said means, quantity of mercury and electrodes being so proportion as to cooperate to close the circuit through the electrodes after said means remains at rest for a predetermined period of time at any point in its movement.

16. A front contact relay adapted to open and close an electrical circuit whenever the relay is intermittently operated at or above a predetermined frequency, said relay comprising the combination of a container, a pair of electrodes in the container, a quantity of mercury in the container,

the mercury to open the circuit through the elecmovable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through the electrodes, and a coil for operating said movable means to shift the mercury to close the circuit through the electrodes when the coil is energized and open the circuit when the coil is deenergized, said means, quantity of mercury and electrodes being so proportioned as to cooperate to close the circuit through the electrodes after said coil remains deenergized for a predetermined period of time.

17. A front contact relay adapted to open and close an electrical circuit whenever the relay is intermittently operated at or above a predetermined frequency, said relay comprising the combination oi. a container, a pair of electrodes in the container, a quantity of mercury in the container, movable means for shifting the mercury with relation to the electrodes to close or open the electrical circuit through the electrodes, a time delay device associated with the container, and a coil for operating said movable means to shift the mercury to close the circuit through the electrodes when the coil is energized and open the circuit when the coil is de-energized, said means, quantity of mercury and electrodes being so proportioned as to cooperate with the time delay device to close the circuit through the electrodes after said coil remains deenergized for a predetermined period of time.

CARL H. LARSON. 

